MORPHOLOGY:
This nocturnal species has large eyes and large ears that are mobile. Dian's tarsier has a special adaptation in its neck vertebrae to help it turn its head 180 degrees. It needs to do this because its eyes can not move. The dental formula of this species is 2:1:3:3 on the upper jaw and 1:1:3:3 on the lower jaw (Nowak, 1999). This species has relatively small upper canines (Nowak, 1999). The tail of this species is naked except for a tuft of hair at the end. This species receives its name from the elongated tarsus bone. The ears of this species are shorter and less narrow as compared to Tarsius spectrum (Niemitz et al., 1991). Females have two pairs of mammae, one inguinal and one pectoral. Dian's tarsier has a pelage that is colored grayish-buff (Niemitz et al., 1991). The sides of the upper lip and in the middle of the lower lip there are short white hairs (Niemitz et al., 1991). The eyes tend to be more symmetrical than other members of the genus Tarsius (Niemitz et al., 1991).

RANGE:
Dian's tarsier is found on the island of Sulawesi (Niemitz et al., 1991). This species lives in primary rain forests (Niemitz et al., 1991). This species was also found to inhabit secondary rainforests (Gursky, 1998).

This species is found in the following protected areas on the island of Sulawesi (Gursky, 1998):

Lore Lindu National Park

Morowali Nature Reserve

ECOLOGY:
This species is a carnivorous species. This species was found not to sleep in the same sleeping site on consecutive days (Niemitz et al., 1991). Although Tremble et al. (1993) did find that this species returns to the same sleeping site. This species tends to sleep in groups (Tremble et al., 1993). The sleeping sites are dense foliage and tree cavities (Tremble et al., 1993). This is a nocturnal and an arboreal species. It was found that this species spends 23% of its time above 3 meters (Tremble et al., 1993). During the night Dian's tarsier will spend 44% of the time foraging, 28% traveling, 21% resting, and 7% grooming (Tremble et al., 1993).

LOCOMOTION:
This species is a vertical clinger and leaper. This species also moves by hopping, quadrupedalism, and cantering (Tremble et al., 1993). This species often rests using oblique and horizontal supports (Tremble et al., 1993). Dian's tarsier uses supports of less than 3 centimeters 70% of the time (Sussman, 1999).

SOCIAL BEHAVIOR:
This species has been reported to live in groups (Tremble et al., 1993).

VOCAL COMMUNICATION:male-female duet: This is a duet that is performed by both the male and female of a pair, at the sleeping site before sunrise (Niemitz et al., 1991). The individual calls of the male and female for this duet are different from one another (Niemitz et al., 1991). In the female call, at the beginning she decreases the frequency pitch (16 to 9 kilohertz), and in the middle the frequency range decreases from 7-8 to 1 kilohertz (Niemitz et al., 1991). Then at the end of the duet, the female will increase both the frequency pitch (9 to 16+ kilohertz) and range (1 to 9+ kilohertz) (Niemitz et al., 1991). In the male call, at the beginning the call has a maximum frequency pitch of 10 kilohertz that falls to 5 kilohertz, and then the frequency pitch increases steadily until at the end of the song it is at 14 kilohertz (Niemitz et al., 1991). This duet has a mean duration of 45 seconds (Niemitz et al., 1991).

OLFACTORY COMMUNICATION:urine mark: This is when an individual will scent mark with urine (Tremble et al., 1993).